Hot top



Feb. 24, 1953 w. F. MILBURN HOT TOP Filed Jan. 12, 1950 of generallyoutside dimensions slightly smaller than the in- Patented Feb. 24, 1953UNITED STATES PATENT OFFICE HOT TOP Walter F. Milburn, Chicago, Ill.

Application January 12, 1950, Serial No. 138,162

4 Claims. (01. 22-147) This invention relates to a so-called hot topwhich comprises a tubular metal casing lined with ceramic or refractorymaterial and adapted to be received in the top opening of an ingot moldto retain a body of molten metal and feed the ingot during congealingthereof.

The primary object of the invention is to provide a hot top which isadapted to feed an ingot in a generally rectangular mold moreeffectively than the hot tops used heretofore.

Another object is to shape the lining of the hot top in a novel mannerso as to reduce the rate of cooling of the molten metal therein ascompared to prior hot top constructions.

A more detailed object is to shape the internal wall of the refractorylining adjacent the bottom thereof in a novel manner to enable theremaining major length of the wall to be cylindrical in contour and yetinsure complete filling of all parts of the mold with molten metal fromthe hot top.

The invention also resides in the novel manner of protecting the metalcasing of the hot top from contact with metal in the mold and supportingthe hot top in a centered position in the mold, and in the novelcharacter of the means for supporting the refractory lining in thecasing.

Other objects and advantages of the invention will become apparent fromthe following detailed description taken in connection with theaccompanying drawings, in which Figure l is a plan View of a hot topconstruction embodying the novel features of the present invention andshown in pouring position in the along the line 66 of Fig. 4.

In the drawings, the invention is shown for purposes of illustration ina hot top comprising a generally tubular cast metal casing l having atubular lining H therein of refractory or ceramic material defining acentral feeder recess 1 E2. The base or lower portion [3 of the casingl0 conforms in cross-sectional shape to the internal contour of theingot mold M on which the hot top is to be used. To fit the base l3loosely within the upper open end of the mold, it is made rectangularcross section with 2 terior of the mold so as to leave a small clearance[5.

In accordance with the present invention, the refractory hot top liningH has an internal contour different than the internal cross section ofthe mold l4 and somewhat smaller in diameter so as to minimize theinternal surface area and thereby reduce, as compared to prior hot topconstructions, the rate of cooling of the molten metal whereby to insuremore effective feeding of the ingot as the metal solidifies in the moldHi. To these ends, the internal wall 16 of the lining II issubstantially circular in cross section and generally cylindrical fromthe upper end thereof to a point adjacent but short of the hot topbottom, and the remaining bottom portion of the lining is flaredoutwardly and downwardly to merge the lining wall with the rectangularinternal contour of the mold.

Herein, the cylindrical and flared portions of the lining wall it areformed as separate pieces of refractory material, the upper one being agenerally cylindrical tube ll of uniform thickness flared downwardlyslightly to provide the necessary internal draft for permitting the hottop to be lifted off from the solidified ingot. This tube is enclosed byand retained in the correspondingly shaped upper portion l8 of the metalcasing It, this portion being substantially smaller in diameter than thelower end or base I3 which is in the form of an external flange of therectangular shape described above and of a depth correspondingapproximately to the thickness of a ring-like member it of refractorymaterial forming the lower portion of the lining ll. Lugs 39 are formedon the exterior of the upper part of the casing It) to facilitateattachment of hoisting cables for handling the hot top.

To merge the cylindrical wall [5 of the hot top lining with therectangular wall 20 of the mold It, the interior of the refractoryringlike member I!) is flared outwardly and downwardly preferably aroundits entire inner periphery. In this instance, the internal wall of themember I9 is pyramidal in shape having generally flat sides 2! flaringgradually outward adjacent the four sides of the rectangular bases l3and merging gradually into corners 22 which extend well into the cornersof the hollow base flange I3. At its upper end, the internal wall of thelower refractory part 19 is clrcular in cross section and has the samediameter as the lower end of the cylindrical internal wall of the upperlining part IT. The upper and lower refractory parts I! and I9 aredisposed in end to end abutment and the external surface of the liningthus formed flares downwardly slightly throughout its length and fitsquite loosely in the corresponding flared interior of the casing It).The lining is supported on ledges 22 projecting inwardly from the lowerend of the base flange I3 and secured detachably to the latter to enablethe lining to be removed from the casing I and replaced from time totime.

In the present instance, the ledges comprise flanges on a series ofL-shaped brackets 23 and are fed into the bottom of the ring member I9so as to be flush with the lower end surface of the hot top lining. Thebrackets are spaced uniformly around the refractory ring I9 andpreferably bear against reinforcing bars 24 of metal embedded in thering in the molding thereof. The other legs of the brackets projectupwardly between the exterior of the ring I9 and the interior of thebase flange l3 and are apertured to receive removable pins 25 whichproject outwardly through holes 26 in the flange |3. After removal ofthe pins 25, the brackets 23 and the lining may be withdrawn endwisefrom the bottom of the casing ID.

The hot top is adapted to be supported on the mold in a novel manner toenable the corners of the base |3 to be centered relative to the cornersof the mold whereby the clearance I between the casing and the mold issubstantially uniform. For this purpose, each corner of the base I3 isbeveled as indicated at 21 and formed with one or more inwardlyextending holes 28 adapted to receive a pin 29 which rests on the top ofthe mold. The beveled corners of the casing cooperate with the walls ofthe mold at the corners of the latter to form a recess (Fig. 6) adaptedto receive a shoulder 30 carried by the pin 29 and engageable with theside walls of the mold to space the sides of the casing baseequidistantly from the mold walls. In the present instance, each pin isL-shaped to facilitate its removal from the casing, and the shoulder 30thereon is in the form of a washer which is pressed onto the pin andlies flat against the beveled corner surface 21. To permit the hot topto be supported at different depths below the top of the mold, a seriesof the holes 28 may be formed along each of the corners 27.

A novel means is provided for covering and shielding the lower end ofthe metal casing flange I3 so as to protect the latter from contact withthe molten metal. For this purpose, a ring-like band 3| of moldedrefractory material fits snugly around the inner periphery of the moldand is suspended from the top of the latter. The band comprises a seriesof bars of refractory material arranged end to end around the interiorof the mold and mitered at the corners as shown in Fig. 2. Each barrests in V-shaped seats formed by upright intermediate portions andupwardly inclined end portions 32 of two Z-shaped strap-like hangers 33composed of readily fusible metal. The other end portion of each hangerprojects outwardly and hooks over the upper end of the mold. The outerface of each bar is recessed to receive the upright intermediate portionof the supporting hangers. Preferably, each bar is reinforced by a metalrod 34.

The cross section of the bars is a right triangle having one side whichfits flatly against the lower end of the hot top and overlaps the endsof both the metal casing flange l3 and the refractory lining member l9,being of a width approximate- 1y equal to the sum of widths of theexposed end of the member I 9 at the narrowest points around the latterand the end of the casing flange (see Fig. 5). Thus, the downwardly andoutwardly inclined inner faces of the bars 3| substantially merge withthe flared surfaces 2| and 22 of the hot top lining and thus constitutedownwardly flared continuations of the lining wall. As a result, thereare no pockets or abrupt corners along the refractory wall which will inany way interfere with the free flow of metal from the hot top into themold even while the metal in the latter is partially solidified.

In use, the hot top is mounted on the mold in the manner described aboveand molten metal is poured into the mold through the hot top which isfilled to a level well above the top of the mold thus filling completelythe recesses or flared portions 2| and 22 of the hot top lining. Then,the supporting pins 29 are withdrawn from the holes 28 in the base |3 topermit the hot top to float on the molten metal which melts away themetal of the hangers 33 so that the sealing band 3| also floats on themetal in the mold.

As the metal around the outside of the ingot begins to congeal theshrinkage at the top of the mold is made up by the flow of molten metalfrom the hot top. During the slow cooling of the metal in the hot topachieved by virtue of the generally cylindrical shape of the upper partof the lining II, this metal remains in the liquid state for a prolongedperiod and continues to fill all of the parts of the mold. Such freeoutward flow of the metal even after substantial shrinking of the latteris facilitated by the gradual downward flaring of the interior of thehot top lining from the cylindrical part thereof all the way down to thewall of the ingot mold.

I claim as my invention:

1. A hot top comprising a tubular metallic casing having a base portionof generally rectangular cross section, an upper tubular section ofrefractory lining material around the interior of said casing extendingto a point adjacent but short of the bottom of the latter and having agenerally cylindrical internal wall, and a tubular lower lining sectionof refractory material rectangularly shaped on its exterior and fittinginto said base portion of said casing in abutment with the bottom ofsaid upper lining section, said lower lining section having an innerperipheral wall of generally circular cross section at its top to mergewith the generally cylindrical internal wall of said upper section andflaring outwardly and downwardly therefrom into the corners of said baseportion to be of rectangular cross section at its bottom.

2. A hot top comprising a tubular metallic casing having a base portionof generally rectangular cross section, and a tubular lining ofrefractory material around the interior of said casing extending to apoint adjacent the bottom of the latter and having a generallycontinuous internal wall which is generally cylindrical in shape fromthe top of the lining substantially throughout its length to a pointadjacent but short of the lower end of said casing, the remaining lowerpart of said lining wall being of rectangular cross section at thebottom and being flared outwardly and downwardly from the generallycylindrical upper portion into the corners of said casing base portion.

3. A hot top for use with an ingot mold having a generally rectangulartop opening defined by side walls, said hot top comprising, a tubularcasing having a base portion of. generally rectangular cross-sectioncorresponding to the shape of the top opening of the mold and adapted tofit loosely into the latter, each of the corners of said base portionbeing formed with inwardly extending holes spaced therealong and adaptedto receive a support pin engageable with the top of the mold at a cornerthereof for supporting said casing in the mold, and a tubular refractorylining extending around the interior of said casing, said casing cornersbeing beveled to cooperate with the side walls of said mold to formrecesses adapted to receive flanges carried by said pins and engageablewith said side Walls to center said base portion in said mold opening.

4. A hot top for use with an ingot mold having a generally rectangulartop opening therein defined by side walls, said hot top comprising, atubular casing having a generally rectangular base portion adapted tofit within said mold opening with a clearance between the base portionand the mold, the corners of said base portion having inwardly extendingholes therein adapted to receive pins engageable with the top of saidmold for supporting said casing thereon, and a tubular lining ofrefractory material within said casing, at least two of thediametrically opposed ones of said pins having shoulders thereonconforming to the contour of the corners of said 6 base portion andengageable with the inner side of said mold walls to cooperate with thelatter and center the base portion in said mold opening.

WALTER F. MILBURN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,431,803 Howard et al Oct. 10,1922 1,523,208 Howard at al. Jan. 13, 1925 1,804,204 Charman et a1. May5, 1931 1,804,208 Charman May 5, 1931 1,921,729 Charman Aug. 8, 19331,921,731 Charman Aug. 8, 1933 1,994,683 Brown Mar. 19, 1935 2,030,199Charman Feb. 11, 1936 2,080,848 Charman May 18, 1937 2,263,437 CameronNov. 18, 1941 2,465,977 Marburg Mar. 29, 1949 FOREIGN PATENTS NumberCountry Date 228,016 Great Britain Jan. 29, 1925 326,785 Great BritainMar. 19, 1930

